[R-meta] Negative r value for effect sizes within studies

[Stefanou Revesz]

Dear All,

This may be too basic to ask. But can the r value chosen to represent
the common correlation among effect sizes within studies be a negative
one?

For example, is there a situation where I would need to use the following?

impute_covariance_matrix(..., r = -.6)

Thank you,
Stefanou